The present invention relates to a supported catalyst for decomposing ozone in gases at temperatures below about 50 .degree. C., to a method for producing a supported catalyst for decomposing ozone in gases, and to a method for catalytically decomposing ozone using a polymer foam supported catalyst.
Ozone, a molecule comprising three oxygen atoms, is used in industrial processes and serves, for instance, as a bleaching agent for oils, fibers or paper, for disinfecting swimming pool water and for cleaning industrial waste water. It also forms in an undesired manner due to the action of ionizing or ultraviolet radiation on atmospheric oxygen, e.g. in the vicinity of electron beam sources, for instance in copiers or around mercury quartz lamps or sunray lamps. Furthermore, it occurs in nature, for instance in the stratosphere, but also on the ground, particularly in "smog" weather conditions.
Ozone is extremely toxic and also very reactive. The ozone content in the exhaust air of industrial plants, for instance in the exhaust air which is produced during oil refining or when disinfecting raw water or waste water, should be reduced where possible in order to protect the environment. Of course, ozone is also highly problematic for health reasons in inhaled air, for instance in fresh air taken from the stratosphere for supplying high-flying aircraft, or close to the ground in smoggy weather conditions. The desirable decomposition of the ozone in industrial waste gases or inhaled air is predominantly effected by catalysis. Many metals, in particular platinum group metals, e.g. palladium or platinum, and metal oxides, for instance transition metal oxides, have been used in pure form or as a mixture as catalytically active components in catalysts for decomposing ozone, for instance in the form of bulk supported catalysts. Mixed metal oxides are highly suitable, particularly mixtures containing manganese dioxide and copper oxide which have become known as "hopcalites". Hopcalites may consist of manganese dioxide and copper oxide, but they may also contain additional metal oxides, for instance nickel oxide, cobalt oxide or silver oxide, and, if desired, promoters such as lithium oxide and/or potassium oxide.